/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.tomcat.websocket.server;

import javax.servlet.*;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;

/**
 * Handles the initial HTTP connection for WebSocket connections.
 */
public class WsFilter implements Filter {

	private WsServerContainer sc;

	@Override
	public void init(FilterConfig filterConfig) throws ServletException {
		sc = (WsServerContainer) filterConfig.getServletContext().getAttribute(
				Constants.SERVER_CONTAINER_SERVLET_CONTEXT_ATTRIBUTE);
	}

	@Override
	public void doFilter(ServletRequest request, ServletResponse response,
	                     FilterChain chain) throws IOException, ServletException {

		// This filter only needs to handle WebSocket upgrade requests
		if (!sc.areEndpointsRegistered() ||
				!UpgradeUtil.isWebSocketUpgradeRequest(request, response)) {
			chain.doFilter(request, response);
			return;
		}

		// HTTP request with an upgrade header for WebSocket present
		HttpServletRequest req = (HttpServletRequest) request;
		HttpServletResponse resp = (HttpServletResponse) response;

		// Check to see if this WebSocket implementation has a matching mapping
		String path;
		String pathInfo = req.getPathInfo();
		if (pathInfo == null) {
			path = req.getServletPath();
		} else {
			path = req.getServletPath() + pathInfo;
		}
		WsMappingResult mappingResult = sc.findMapping(path);

		if (mappingResult == null) {
			// No endpoint registered for the requested path. Let the
			// application handle it (it might redirect or forward for example)
			chain.doFilter(request, response);
			return;
		}

		UpgradeUtil.doUpgrade(sc, req, resp, mappingResult.getConfig(),
				mappingResult.getPathParams());
	}

	@Override
	public void destroy() {
		// NO-OP
	}


}
